ASTM B930-03(2021)
(Test Method)Standard Test Method for Rating Grain Size and Frequency of Abnormally Large Grains in Cemented Tungsten Carbides (Hardmetals)
Standard Test Method for Rating Grain Size and Frequency of Abnormally Large Grains in Cemented Tungsten Carbides (Hardmetals)
SIGNIFICANCE AND USE
5.1 The microstructure and grain growth of cemented tungsten carbides affect the material's mechanical and physical properties. The grain size and distribution will affect the material's wear resistance and fracture toughness. Abnormally large grains as compared to the background may introduce an area of weakness in a sintered part.
5.2 This test method may be used in acceptance testing of cemented tungsten carbide materials or the tungsten carbide powder used in their manufacture. The specified grain size used for the E-Rating is to be agreed upon between purchaser and supplier.
SCOPE
1.1 This test method describes a procedure for measuring abnormally large grains and the frequency of those grains in cemented tungsten carbides (hardmetals).
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
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Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: B930 − 03 (Reapproved 2021)
Standard Test Method for
Rating Grain Size and Frequency of Abnormally Large
Grains in Cemented Tungsten Carbides (Hardmetals)
This standard is issued under the fixed designation B930; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2.2 L-Rating—the size, in µm, of the largest grain ob-
served in a fully-etched specimen.
1.1 This test method describes a procedure for measuring
abnormally large grains and the frequency of those grains in
4. Summary of Test Method
cemented tungsten carbides (hardmetals).
4.1 Apolished and fully etched specimen/specimens having
1.2 This standard does not purport to address all of the
a minimum observable area of 0.5 cm is examined using a
safety concerns, if any, associated with its use. It is the
metallograph. Abnormally large grains, compared to the finer-
responsibility of the user of this standard to establish appro-
grained background material, are identified. These grains are
priate safety, health, and environmental practices and deter-
categorized as: ( 1) The number of grains larger than a
mine the applicability of regulatory limitations prior to use.
specified size, or ( 2) The largest grain observed, or both.
1.3 This international standard was developed in accor-
dance with internationally recognized principles on standard-
5. Significance and Use
ization established in the Decision on Principles for the
5.1 The microstructure and grain growth of cemented tung-
Development of International Standards, Guides and Recom-
sten carbides affect the material’s mechanical and physical
mendations issued by the World Trade Organization Technical
properties. The grain size and distribution will affect the
Barriers to Trade (TBT) Committee.
material’s wear resistance and fracture toughness.Abnormally
large grains as compared to the background may introduce an
2. Referenced Documents
area of weakness in a sintered part.
2.1 ASTM Standards:
5.2 This test method may be used in acceptance testing of
B243 Terminology of Powder Metallurgy
cemented tungsten carbide materials or the tungsten carbide
B406 Test Method for Transverse Rupture Strength of Ce-
powderusedintheirmanufacture.Thespecifiedgrainsizeused
mented Carbides
for the E-Rating is to be agreed upon between purchaser and
B657 GuideforMetallographicIdentificationofMicrostruc-
supplier.
ture in Cemented Carbides
B665 Guide for Metallographic Sample Preparation of Ce-
6. Apparatus
mented Tungsten Carbides
6.1 Metallographic Microscope, capable of magnifications
3. Terminology
of up to 1500×.
3.1 Definitions—Definitions of powder metallurgy terms
6.2 Ordinary metallurgical laboratory equipment.
can be found in Terminology B243.
6.3 Equipment for specimen preparation as outlined in
3.2 Definitions of Terms Specific to This Standard:
Guide B665.
3.2.1 E-Rating—the number/cm of grains larger than a
specified size in a fully-etched specimen. 7. Test Specimens
7.1 Specimen Size—The recommended specimen shall be
the standard transverse rupture specimen as specified in Test
This test method is under the jurisdiction of ASTM Committee B09 on Metal
Method B406; that is, ground to the following dimensions:
Powders and Metal Powder Products and is the direct responsibility of Subcom-
mittee B09.06 on Cemented Carbides.
5.00 6 0.25 mm (0.200 6 0.010 in) thick by 6.25 6 0.25 mm
Current edition approved Sept. 1, 202
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